1. Field of Invention
The present invention relates to a technical field of GaN series light-emitting diode (LED) structure, more specifically to a GaN series high light-emitting efficiency LED structure with an interface blocking layer structure formed under the light-emitting layer.
2. Description of the Related Art
As shown in FIG. 1, the structure of GaN series LED includes a sapphire substrate 10, a GaN buffer layer 11, an n-type doping GaN ohmic contact layer 12, an indium gallium nitride (InGaN) light-emitting layer 13, and a p-type doping GaN layer 14. Then, through photolithography and etching processes, the n-type doping GaN ohmic contact layer 12, the InGaN light-emitting layer 13 and the p-type doping GaN layer 14 are partially removed to expose a partial surface of the n-type doping GaN ohmic contact layer 12. In addition, a transparent conductive layer 15 is formed over the p-type doping GaN layer 14; a p-type metal electrode 16 is disposed over the transparent conductive layer 15; and an n-type metal electrode 17 is disposed on the surface of the n-type doping GaN ohmic contact layer 12. Thus, the so-called conventional lateral electrode structure of the GaN series LED is formed.
Referring now to FIG. 2, the structural schematic view includes a sapphire substrate 20, a GaN buffer layer 21, an n-type doping GaN ohmic contact layer 22, an n-type doping aluminum indium gallium nitride superlattice stacked structure 23, an InGaN light-emitting layer 24, a p-type doping GaN layer 25, a transparent conductive layer 26, a p-type metal electrode 27, and an n-type metal electrode 28. Wherein, the n-type doping aluminum indium gallium nitride superlattice stacked structure 23 is composed of a number of aluminum indium gallium nitride layers with different thicknesses and composition, and the thickness difference is less than or equal to 50 Å.
Moreover, referring now to FIG. 3, it is a structural schematic view showing another GaN series LED disclosed by a prior art for improving light-emitting efficiency. The GaN series LED element includes an InGaN multiple quantum well (MQW) light-emitting layer 200 with periodic thickness variance, which is formed over an n-type doping GaN layer 100. The n-type doping GaN layer 100 is composed of an n-type doping GaN layer 100a with a growth temperature ranging from 1000 to 1050° C., and an n-type doping GaN layer 100b with a relative growth temperature ranging from 880 to 920° C.; the MQW light-emitting layer 200 produces periodic thickness variance because the added n-type doping GaN layer 100b grows in low temperature, and the preferred thickness of the n-type doping GaN layer 100b is about 1000 Å. However, the light-emitting efficiency of the conventional LED is still limited, and there is a need for further improvement.